Laryngoscopes are widely used to assist with tracheal intubation. A conventional laryngoscope consists of a handle and a blade connected pivotably at the head of the handle. The blade is movable between an operative position, in which it projects out laterally, and a folded position in which it lies down against the side of the handle. In typical use a clinician standing above/behind the head of the supine patient holds the laryngoscope in one hand, blade-downwards with the blade underside away from them, and the breathing tube in the other hand. The blade is put down the patient's throat and turned and lifted by forcible tilting of the handle to move the tongue and epiglottis out of the way. The blade carries a light. The breathing tube is slid in along the upper side of the blade, which may be shaped to guide this. Visibility—assisted by the light—is critical to ensure that the tube has indeed entered the trachea. Note: the terms upper side and underside are used in relation to the blade as it would be with the handle vertical and head upwards, and the blade projecting in the operating position. During actual use as described, the upper side would be inclined down.
Intubation is almost always urgent. For this reason although many blade designs exist clinicians generally prefer to use a familiar one. Care is needed not to damage the front teeth by using them as a reaction point for the rear end of the blade when lifting the tongue. With the urgent situation and substantial force applied, there is a possibility of minor abrasions in the mouth or throat so sterility is important. Many laryngoscopes are now “single use”: sometimes just the blade and sometimes the entire instrument. Otherwise, a laryngoscope might contribute to carrying infection from the patient to another patient.
Two kinds of light emitter are conventional. Each uses a power source, specifically a battery, in the shaft of the handle. In one kind the head of the handle has an upwardly-directed lamp (bulb or LED) beneath the pivot joint with the blade, and the blade has an optical fibre bundle leading from its rear end to the emitter position towards the tip. Pivoting the handle to the operative position switches on the lamp and presents the proximal end of the optical fibres to the handle lamp so that light is emitted at the front of the blade. In the other kind the light emitter on the blade is itself a lamp, such as a filament bulb or LED, and the blade rear end and handle head have respective contacts which engage when the blade is swung to the operating position to turn on the lamp.
Moulded plastic blades have obvious manufacturing advantages, but limited clinical acceptability because of concerns about bending and breakage. Metal blades are widely used, as single-use blades and in single-use instruments.
Many known laryngoscopes have detachable blades with a standard hook-on fitting to a pivot bar mounted across the head of the handle. A range of blades may be usable with a single handle.
With single-use laryngoscopes, difficulties may arise with disposal regulations. For example a single-use handle may be adapted to prevent removal of the batteries—to prevent repeated use—but this prevents disposal if local laws require recycling of batteries.